Binder resin for toner and toners

ABSTRACT

A binder resin for toner which is excellent in low-temperature fixing property and offset resistance as well as smear resistance, while responding to the demand of the market from the perspectives of environmental protection, such as being free from a bisphenol A structure and tin, and a toner using the same. The binder resin for toner can be obtained using a catalyst containing titanium or germanium, preferably comprises the structure derived from branched or alicyclic alcohols, and comprises the structure derived from terephthalic acid as the acid component, which represents greater than or equal to 60 mol % with respect to the number of moles of all acid components, and a toner using the same.

TECHNICAL FIELD

The present invention relates to a polyester-based binder resin fortoner and a toner. More particularly, the present invention relates to abinder resin for an electrophotographic toner which provides highlybalanced performance for toner, such as hot offset resistance, fixingproperty or the like, and an electrophotographic toner.

BACKGROUND ART

Recently, the performance required from copier machines or printersusing electrophotography has highly increased. In general,electrophotography for copiers or printers involves a method in which alatent electrostatic image is formed on a photoconductor, subsequentlythe latent image is developed using the toner, the toner image istransferred onto a sheet to be fixed, for example, paper, and then thesheet is hot-pressed by means of a heat roller (heat roller fixingmethod). In this heat roller fixing method, improved economic situationsuch as in electricity consumption, increased copying speed and the likehave led to a demand for a toner with good fixing property to fix theimage at lower temperatures. On the other hand, in the heat rollerfixing method, there is a problem of so-called the offset phenomenon inwhich since the surface of the heat roller is brought into contact withthe toner in a molten state, the toner adheres and is transferred to thesurface of the heat roller, and this adhered toner is re-transferred toa subsequent sheet to be fixed, making the sheet contaminated. Thefeature of not causing this offset phenomenon is one of demands for theimportant toner performance. Moreover, copiers and printers with higherspeeds increasingly require better performance in the charging area.Thus, a toner needs much higher durability, and therefore long-termstability in plate wear is required.

Generally, there is an attempt to lower the fixing temperature bylowering the molecular weight of binding resins (binder resins), inorder to make the fixing property better. However, although lowering ofthe molecular weight decreases the resin viscosity, it also decreasesthe resin strength and the cohesive power of resin at the same time,resulting in problems such as decreased toner durability and the offsetphenomenon occurring about the fixing roller. In addition, there havebeen attempts to use as such a binding resin, a mixture of a highmolecular weight resin and a low molecular weight resin, such that themixture has a broad molecular weight distribution, or to use a binderresin with the high molecular weight portion further crosslinked.However, in these methods, the viscosity of the resin is increased, andto the contrary to the above case, it is difficult to satisfy the fixingquality.

A variety of toners have been suggested which use, instead of thosestyrene-acrylic resins that have been predominantly used hitherto assuch binding resins required of contradictory functions, polyesterresins that are rather of higher density as binder resins, (see, forexample, Japanese Unexamined Patent Application Publication Nos.61-284771 and 62-291668, Japanese Examined Patent ApplicationPublication Nos. 7-101318, 8-3663, and U.S. Pat. No. 4,833,057);however, presently it cannot be stated that they sufficiently satisfy,in particular, the recent increasing demands of the market. Moreover, asit is being considered proper in the market to use double-sided printingand double-sided copying in view of saving resources and protecting theenvironment, from this point of view there is a demand on an improvementin smear resistance, in addition to the fixing property and the offsetresistance.

In addition, there have been conventionally used, bisphenol Aderivatives as a raw material of a toner using a polyester resin, ortin-based catalysts as the catalyst for preparation of polyester.Meanwhile, there is a recent demand in the market from the perspectiveof environmental protection, on products that do not contain bisphenolA, tin or the like, as there is an opinion that these substances mayhave adverse effects on the environment in various ways.

Furthermore, from another perspective of saving resources, owing to theexhaustion of resources associated with recent increase in populationand extension in energy consumption, saving of resources and energy aswell as recycling of resources are highly desired. PET bottles, interalia, that are collected from local communities are increasingly used intextiles or containers, and there is also a demand for furtherdevelopment of new applications.

DISCLOSURE OF INVENTION

Therefore, it is an object of the present invention to provide a binderresin for toner and a toner having high performance, especiallyexcellent smear resistance, while responding to the demand of the marketfor the saving of resources and environmental protection.

The inventors have conducted an extensive investigation in order toachieve the above object and have accomplished the invention asdescribed below.

Thus, the first aspect of the present invention is a binder resin fortoner comprising a polyester structure consisting at least of astructure derived from carboxylic acid and a structure derived fromalcohol, characterized in that

it contains the structural unit of the following formula [I] in anamount of 1 mol % or less with respect to all the structural unitsderived from alcohol:

the content of tin is 5 ppm or less;

the content of an element selected from titanium, germanium and aluminumis 10 ppm to 1500 ppm; and

the melting temperature is greater than or equal to 110° C.

The second aspect of the present invention is a binder resin for toner,characterized in that it contains 0.1 to 10 mol % of a structural unitderived from an isocyanate compound, when the sum of all the structuralunits derived from carboxylic acid and of all the structural unitsderived from alcohol is taken to be 100 mol %.

The third aspect of the present invention is a binder resin for tonercontaining 0 to 40% by mass of THF-insoluble components, and 100 to 60%by mass of THF-soluble components.

The fourth aspect of the present invention is a binder resin for tonercharacterized in that

at least 60 mol % of the structure derived from carboxylic acidcomprises a structure derived from terephthalic acid,

at least 40 mol % of the structural units derived from alcohol comprisesa structure derived from ethylene glycol, and

at least 75 mol % of the structural units derived from alcohol comprisesstructures derived from ethylene glycol and neopentyl glycol.

The fifth aspect of the present invention is a binder resin for tonercomprising a structure of polyester consisting at least of a structurederived from carboxylic acid and a structure derived from alcohol,characterized in that it is obtained

from 10 to 60% by mass of polyester resin (A) having an OH number of 30to 90 KOH mg/g and glass transition temperature of 0 to 50 C, and

40 to 90% by mass of polyester resin (B) having an OH number of lessthan or equal to 10 KOH mg/g and a weight-average molecular weight of1000 to 4000, and also having at least 10 mol % of the structural unitderived from isophthalic acid, with respect to 100 mol % thatcorresponds to the sum of all structural units derived from the alcoholsconstituting the polyester, and

from polyvalent isocyanate;

it contains the structural unit of the following formula [I] in anamount of 1 mol % or less with respect to all alcohol-derived structuralunits:

the melting temperature is greater than or equal to 110 C.

The sixth aspect of the present invention is a binder resin for tonercharacterized in that the number-average molecular weight of polyester(A) is 1000 to 4000, it contains 2 to 20 mol % of a structural unitderived from polyvalent alcohol with a molecular valence of 3 or higher,with respect to 100 mol % that corresponds to the sum of all unitsderived from the alcohols constituting the polyester, and

the glass transition temperature of polyester (B) is 40 to 80 C.

The seventh aspect of the present invention is toners using theabove-described binder resin for toner.

Since it is possible to obtain a binder resin for toner that has a lowlevel of the bisphenol A structure and high performance such asexcellent smear resistance according to these aspects of the invention,the industrial significance of the present invention is great.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the first to fourth aspects of the present invention willbe first described in detail. Herein, the term “structural unit” will besometimes simply referred to as “structure”.

The binder resin for toner used in the present invention ischaracterized in that it has a structure of polyester, the structuralunit of the following formula [I] is contained in an amount of 1 mol %or less with respect to all alcohol-derived structural units, thecontent of tin is less than or equal to 5 ppm, and the content of anelement selected from titanium, germanium and aluminum is 10 ppm to 1500ppm.

More particularly, it is preferred that the binder resin for toner ofthe present invention has the following constitution:

a polyester resin having a repeating structural unit represented byformula [[A]COO[B]O(CO)],

wherein [Structure A] is a structure having an aliphatic, alicyclic oraromatic structure,

at least 99 mol % of [Structure B] has the structure of formula [II]:

wherein, Ar is a group having an aromatic structure,0≦m1≦1, 0≦m2≦1,2≦n≦20, andR¹-R^(2n+2) are groups consisting of elements selected from carbon,hydrogen, oxygen, nitrogen, phosphorous and silicon, and/or covalentbonds, and they may join together to form a cyclic structure or a(double) bond;

the content of tin is less than or equal to 5 ppm; and

the content of an element selected from titanium, germanium and aluminumis 10 ppm −1500 ppm.

The polyester resin of the present invention is typically obtained bythe polycondensation reaction of a polybasic carboxylic acid or an acidanhydride thereof with a specific polyvalent alcohol. [Structure A] isderived from the carboxylic acid, and [Structure B] is derived from thealcohol.

For the carboxylic acid, preferred is a hydrocarbon compound having 1 to20 carbon atoms in which 1 to 5 hydrogen atoms, preferably 1 to 3hydrogen atoms are substituted by carboxylic acid groups. It ispreferred that this hydrocarbon is an aliphatic, alicyclic or aromatichydrocarbon. Specific examples include aliphatic dicarboxylic acids suchas malonic acid, succinic acid, glutaric acid, adipic acid, azelaic acidand sebacic acid; unsaturated dicarboxylic acids such as maleic acid,fumaric acid, citraconic acid and itaconic acid; alicyclic dicarboxlicacids such as cyclohexanedicarboxylic acid; aromatic dicarboxlic acidssuch as terephthalic acid and isophthalic acid; and anhydrides of thesedicarboxylic acids such as phthalic anhydride. It is also possible touse lower alkyl esters of these dicarboxylic acids in thepolycondensation reaction. These lower alkyl esters may be used toobtain polyesters by the polycondensation reaction bytransesterification with the polyvalent alcohols described below. Amongthese, preferred are aromatic dicarboxylic acids, and more preferably,terephthalic acid and isophthalic acid.

The polybasic carboxylic acids may be used in combination of two or morespecies.

It is also possible to use a monobasic carboxylic acid and a polybasiccarboxylic acid for the purpose of controlling the molecular weight. Aspreferred monobasic carboxylic acids, mention may be made of aliphaticcarboxylic acids such as octanoic acid, decanoic acid, dodecanoic acid,myristic acid, palmitic acid and stearic acid, and such acids may beoptionally branched and may optionally have unsaturation. Further, thesealiphatic monobasic carboxylic acids are preferably used to adjust theglass transition temperature since they have the property of loweringthe grass transition temperature. In addition, aromatic carboxylic acidssuch as benzoic acid or naphthalenecarboxylic acid may be used. Thesemonobasic carboxylic acids are used in an amount of from 0 to 30 mol %,preferably 0 to 15 mol %, relative to all carboxylic acids.

The monobasic carboxylic acid may be used in combination of two or morespecies.

Polybasic carboxylic acids with a molecular valence of 3 or higher arepreferably used, since they have the effect of broadening the molecularweight distribution that will be described later, or the effect ofinhibiting crystallization of resins. In particular, mention may be madeof trimellitic acid, pyromellitic acid and their acid anhydrides, andespecially trimellitic acid and its acid anhydride are preferred. Thesepolybasic carboxylic acids with a molecular valence of 3 or higher areused in an amount of 0 to 30 mol %, preferably 1 to 30 mol %, morepreferably 1 to 10 mol %, especially 2 to 10 mol %, relative to allcarboxylic acids.

It is also possible to use them in combination of two or more species.

In the present invention, the [Structure A] portion of the polyesterresin preferably is a structural unit derived from carboxylic acid andpreferably has a structure in which 60 mol % or more of all thestructural units derived from carboxylic acid comprise a structurederived from terephthalic acid, in view of the method of preparation ofpolyester resins using PET resins or the like as the raw material, whichis to be described later, the cost of raw materials or supply stabilityassociated with said method, as well as the toner performance. Inaddition, although it is possible to use those that are traditionallyused in the preparation of polyester resins, it is preferable not to useany structure having the bisphenol A skeleton.

The alcohol preferably comprises a structure of the following formula[II]:

wherein, Ar is a group having an aromatic structure,0≦m1≦1, 0≦m2≦1,2≦n≦20, andR¹ to R^(2n+2) are groups consisting of elements selected from carbon,hydrogen, oxygen, nitrogen, phosphorous and silicon, and/or covalentbonds, and they may join together to form a cyclic structure or a(double) bond.

For the alcohol, mention may be made specifically of polyvalent alcoholssuch as ethylene glycol, 1,4-butanediol, 1,2-propylene glycol,1,3-propylene glycol, 1,3-butanediol, 2,3-butanediol, diethylene glycol,triethylene glycol, dipropylene glycol, 1,5-pentanediol, 1,6-hexanediol,neopentyl glycol, 2-ethyl-1,3-hexanediol, trimethylolethane,cyclohexanedimethanol, hydrogenated bisphenol A,1,4-cyclohexanedimethanol, hydroquinone, resorcine and phthalyl alcohol.Among these, preferred are neopentyl glycol, 2-ethyl-1,3-hexanediol,trimethylolethane, cyclohexanedimethanol, hydrogenated bisphenol A and1,4-cyclohexanedimethanol which are branched and/or have cyclicstructures, and particularly preferred is neopentyl glycol.

The polyvalent alcohols may be used in combination of two or morespecies.

These polyvalent alcohols, while being very useful in exhibitingexcellent performance of the binder resin for toner, have a structuredifferent from the structures of the compound with bisphenol A skeleton,in particular, bisphenol A, the bisphenol A-2-propylene oxide adduct,the biosphonel A-3-propylene oxide adduct, the biosphenolA-polypropylene oxide adduct, the bisphenol A-2-ethylene oxide adduct,the bisphenol A-3-ethylene oxide adduct and the biosphenolA-polyethylene oxide adduct. These alcohols with the biosphenol Astructure are used in an amount of 1 mol % or less, preferably of 0 mol%, relative to all alcohols. When said amount exceeds 1 mol %, the smearresistance which will be described later may become insufficient.

It is also possible to use a monovalent alcohol and a polyvalent alcoholwith a molecular valence of 3 or higher for the purpose of controllingthe molecular weight of the polyester. As preferred monovalent alcohols,mention may be made of aliphatic monovalent alcohols such as octanol,decanol, dodecanol, myristyl alcohol, palmityl alcohol and stearylalcohol, and such alcohols may be branched or may have unsaturation.These monovalent alcohols are used in an amount of from 0 to 25 mol %,preferably 0 to 15 mol %, relative to all alcohols.

Polyvalent alcohols with a molecular valence of 3 or higher arepreferably used, since they have the effect of broadening the molecularweight distribution that will be described later, or the effect ofinhibiting crystallization of resins. In particular, mention may be madeof trimethylolpropane, glycerin, 2-methylpropanetriol,trimethylolethane, pentaerythritol, sorbit and sorbitan, and preferredare trimethylolpropane, glycerin, 2-methylpropanetriol andtrimethylolethane, with trimethylolpropane being particularly preferred.These polyvalent alcohols with a molecular valence of 3 or higher areused in an amount of 1 to 25 mol %, preferably 1 to 20 mol %, morepreferably 2 to 12 mol %, especially 2 to 10 mol %, relative to allalcohols.

Said monovalent alcohols or polyvalent alcohols with a molecular valenceof 3 or higher may be used in combination of two or more species.

The polyester resin according to the present invention is typicallyobtained from said polybasic carboxylic acids and polyvalent alcohols,while other polyesters can also be used as the raw material, and it ispreferable to prepare a polyester resin by depolymerization andpolycondensation thereof. Particularly preferred polyester ispolyethylene terephthalate (PET). This PET may be a recycled PET thathas been collected from waste products. A typical recycled PET is oneprocessed in the form of flakes, and its weight-average molecular weightis in the order of 30,000 to 90,000. Such PET is not limited in themolecular weight distribution, composition, method of preparation,morphology at the time of use, or the like, and it is not limited torecycled products.

Upon considering the reactivity of polycondensation to be describedlater, it is preferred that the content of such PET is greater than orequal to 40 mol %, in terms of the number of moles of ethylene glycolwhich is the alcoholic component derived from PET, when the number ofmoles of all alcoholic components in the polyester resin is taken as 100mol %.

Further, it is preferable to comprise, as the alcohol component, atleast ethylene glycol originating from PET, an alcohol having a branchedstructure and/or cyclic structure, and preferably neopentyl glycol; andfor the content thereof, the sum of ethylene glycol, of the alcoholhaving a branched structure and/or cyclic structure, and preferably ofneopentyl glycol is preferably 75 mol % or greater, when the number ofmoles of all alcoholic components is taken as 100 mol %.

The polycondensation reaction in obtaining a polyester resin accordingto the present invention may be carried out by any known method in aninert gas such as nitrogen gas, for example, high temperaturepolycondensation in the absence of solvent, solution polycondensation,or the like. The ratio of the acid monomers and the alcohol monomersused in the reaction, which is expressed as the ratio of the hydroxylgroup of the latter to the carboxyl group of the former, is generally0.7 to 1.4.

Further, when PET is used as the raw material, depolymerization of PETmay be carried out in advance by adding a portion of the alcoholmonomers to PET, and then after the polycondensation reaction may becarried out by adding the remaining portion of the alcohol monomers andthe acid monomers; or alternatively the depolymerization reaction andthe polycondensation reaction may be carried out simultaneously byadding PET, the alcohol monomers and the acid monomers all at once.

A catalyst is used in the process of carrying out the above-mentionedpolycondensation reaction, or carrying out the polycondensation anddepolymerization reactions upon preparation of a polyester resin. Thecatalyst is a catalyst containing an element selected from titanium,germanium and aluminum, and is different from the tin-based catalystssuch as dibutyltin oxide, or the antimony-based catalysts such asantimony trioxide. Among these, preferred is the catalyst containingtitanium and/or germanium, and more preferred is the catalyst containingtitanium. As a catalyst containing titanium, it is more preferred to usetitanium alkoxide, titanium acylate, titanium chelate, or the like, andit is particularly preferred to use tetra-n-butyl titanate,tetra(2-ethylhexyl) titanate, tetramethyl titanate or tetraisopropyltitanate. As a catalyst containing germanium, mention may be made ofgermanium dioxide or the like. Further, the amount of the catalyst addedin this case is preferably 0.01% to 1.00% by mass. The catalysts may beused in combination of two or more species. There is no limit to thetime of using the catalyst, and it may be used from the beginning of thepolycondensation reaction or added during said reaction.

Specific product names of those corresponding to saidtitanium-containing catalysts may exemplified by, but not limited to,Orgatics TA-25 (tetra-n-butyl titanate), TA-30 (tetra(2-ethylhexyl)titanate), TA-70 (tetramethyl titanate), or the like for titaniumalkoxides; Orgatics TPHS (polyhydroxytitanium stearate) or the like fortitanium acylate; and Orgatics TC-401 (titanium tetraacetyl acetate),TC-200 (titanium octylene glycolate), TC-750 (titanium ethylacetoacetate), TC-310 (titanium lactate), TC-400 (titanium triethanolaminate), or the like for titan chelate (all are products of MatsumotoPharmaceutics Industry, Co., Ltd.).

A catalyst containing titanium is of excellent performance as thecatalyst used in the above-mentioned polycondensation anddepolymerization in the presence of polyester. Since a catalystcontaining titanium is deactivated and is deprived of catalytic activityin the case of water being present in the system, such catalyst is knownin general as the catalyst for transesterification reaction. In theprocess of carrying out polycondensation and depolymerization in thepresence of polyester, less water is produced during thepolycondensation reaction, and even if a catalyst containing titanium isused, the deactivation of the catalytic activity is suppressed. This isalso the reason why it is preferred to use the polycondensation reactionand the depolymerization reaction in the presence of polyester, the rawmaterial for which is represented by PET, upon preparation of thepolyester resin according to the present invention using atitanium-containing catalyst.

The polyester resin according to the present invention is preferablyprepared by carrying out polycondensation, or polycondensation anddepolymerization at 200 C to 270 C. A more preferred temperature is inthe range of 220 C to 260 C. When the reaction temperature is below 200C, the solubility of the polyester during depolymerization, the rawmaterial for which is represented by PET, is low, and thus the reactiontime may be prolonged; or the solubility of the acid components such asterephthalic acid in polyvalent alcohols may become low. When thereaction temperature is above 270 C, decomposition of the raw materialsmay occur.

The binder resin for toner according to the present invention that usesthe polyester resin thus obtained contains an element selected fromtitanium, germanium and aluminum in a content of 10 to 1500 ppm, andpreferably 30 to 1000 ppm. Further, the content of tin in said polyesterresin is 0 to 5 ppm. This originates from the tin that may be containedin recycled products when recycled products of polyester are used, theraw material for which is represented by PET. The more preferred valuefor said tin content is 0 ppm.

The analysis of metals in the above-mentioned resin can be confirmedusing any known metal analytic method such as atomic absorptionspectroscopy or plasma luminescence spectroscopy.

As mentioned above, the properties required from a toner include goodfixing property, high strength, high cohesive power, high durability andprevention of offset onto the fixing roller, and as the method of makingthese properties coexist, broadening of the molecular weightdistribution of the binding resin is highly recommended.

The molecular weight distribution can be controlled easily in arelatively broad scope by the use of the above-mentioned polybasiccarboxylic acid with a molecular valence of 3 or higher or polyvalentalcohol with a molecular valence of 3 or higher.

The polyester resin according to the present invention is preferably ofa peak molecular weight in the range of 1,000 to 20,000, inclusive. Whenthe peak molecular weight is less than 1,000, the resin strength andcohesive power may be low, and the durability and offset resistance maybe insufficient. When it is greater than 20,000, the fixing property maybe insufficient.

The polyester resin of the present invention may include resins that areinsoluble in a solvent. The term “solvent-insoluble portion” as usedherein means the portion of the resin that is insoluble when dissolvedin tetrahydrofuran (THF) as the solvent. This THF-insoluble portion ispredominantly the portion of the polyester resin three-dimensionallycrosslinked. The THF-insoluble portion is 0 to 40% by mass, preferably 1to 40% by mass, and more preferably 1 to 25% by mass, while theTHF-soluble portion is 100 to 60% by mass, preferably 99 to 60% by mass,and more preferably 99 to 75% by mass.

The molecular weight distribution of the THF-soluble portion ispreferably 2 to 25, more preferably 2 to 20, and further more preferably3 to 10. Further, the peak molecular weight is preferably in the rangefrom 1000 to 20,000, inclusive. Also, the THF-soluble portion iscontained, preferably among the structural units derived from alcohol,in the ratios of 80 to 100 mol % of the structural unit derived fromdiols (2AU1), and 0 to 20 mol % of the structural unit derived fromtriols (3AU1), when the sum of the structural units derived from saidalcohols is taken to be 100 mol %.

Although the polyester resin containing said THF-insoluble portion has asubstantially broad molecular weight distribution, since a part of theresin becomes insoluble during preparation, the solution viscosity islowered, and thus it may become possible to obtain a polyester resin ofbroad molecular weight distribution with good productivity.

The THF-insoluble portion is contained, preferably among the structuralunits derived from alcohol, in the ratios of 70 to 99 mol % of thestructural unit derived from diols (2AU2), and 1 to 30 mol % of thestructural unit derived from triols (3AU2), when the sum of thestructural units derived from the alcohols is taken to be 100 mol %.

Said THF-insoluble component is what is determined by the methoddescribed in the following Examples, and the proportion of theTHF-soluble component contained therein is substantially less than orequal to 1% by mass. Further, the proportion of the THF-insolublecomponent contained in the THF-soluble component is substantially lessthan or equal to 1% by mass.

As a method of analyzing the structure of the THF-insoluble portion, thefollowing method is preferably used, that is, a method in which theTHF-insoluble portion is hydrolyzed with sulfuric acid or the like, andthen the resulting component is subjected to structure analysis orquantification by any known method such as liquid chromatography (LC),gas chromatography (GC), nuclear magnetic resonance (NMR), infraredspectrometry (IR), or the like.

As a method of analyzing the structure of the THF-soluble portion,structure analysis and quantification may be carried out directly by LC,NMR, IR or the like, in addition to the above-mentioned method.

The polyester resin according to the present invention preferably has0.1 to 10 mol %, and preferably 0.1 to 4 mol % of the structural unitsderived from isocyanate compounds, when the sum of all the structuralunits derived from acid and all the structural units derived fromalcohol of polyester resin is taken to be 100 mol %. The units aremainly introduced by the method in which broadening of the molecularweight distribution is attempted by reacting and crosslinking apolyester resin with a polyvalent isocyanate to produce a component withincreased molecular weight or a solvent-insoluble component (urethaneextension method). As the polyvalent isocyanates used herein, mentionmay be made specifically of diisocyanates such as hexamethylenediisocyanate, isophorone diisocyanate, tolylene diisocyanate,diphenylmethane diisocyanate, xylene diisocyanate, tetramethylenediisocyanate, norbornene diisocyanate, and the like. It is also possibleto use a polyvalent isocyanate with a molecular valence of 3 or higher.It is also possible to use the isocyanates in combination of two or morespecies.

Since the structural units derived from isocyanate compounds have highcohesive power between molecules, having good mechanical durability andexhibiting higher smear resistance is one of the reasons why thestructural units are preferably used.

The isocyanate compounds are used in an amount of 0.1 to 10 mol %, andpreferably 4 mol %, when the sum of all the structural units derivedfrom carboxylic acid and all the structural units derived from alcoholis taken to be 100 mol %.

As a more preferred method of the urethane extension method, mention maybe made of a method in which as a polyester resin, a polyester resinwith a relatively higher OH number (a-0) and a polyester resin with arelatively lower polyester resin (a-2) are used in combination. In thismethod, since the polyester resin (a-0) is more likely to react withisocyanate than polyester resin (a-2), and increase in the molecularweight proceeds with priority, in addition to the effective broadeningof the molecular weight distribution, the molecular weight distributioncan be carried out easily, depending on the ratios of the used amountsof polyester resin (a-0) and of polyester resin (a-2). Upon consideringthe reactivity of the polyvalent isocyanate, the OH number of saidpolyester resin (a-0) has a lower limit of preferably 15 mg KOH/g, andmore preferably 30 mg KOH/g. Meanwhile, the upper limit is preferably 90mg KOH/g, and more preferably 70 mg KOH/g. Also, the OH number ofpolyester resin (a-2) according to the present invention is preferably10 mg KOH/g or less, and more preferably 7 mg KHO/g or less, since thereaction between the polyester resin and the polyvalent isocyanate isnot impeded, and since the finally obtained binder resin for toner iswell-balanced between good fixing property and the offset resistance.

Further, the OH number indicates the number of mg of potassium hydroxiderequired for neutralizing the acid anhydrides in the esterification ofthe OH group in 1 g of the resin. The measurement of the OH number iscarried out by the reverse titration by any known acid anhydrides. Inparticular, the method which uses phthalic acid as the acid anhydrideand imidazole as the catalyst is preferred, and as the solvent todissolve these acid anhydride and catalyst, pyridine is used to form thereaction reagent. As the solvent to dilute the reaction reagent and theresin after reacting them, solvents with high solubility for the resin,such as pyridine or tetrahydrofuran, are used.

The method of using polyester resin (a-0) and polyester resin (a-2) ofthe present invention in combination will be described in detail.

In the above-mentioned method, urethane extension is achieved mainly bya reaction between polyester resin (a-0) and a polyvalent isocyanate,and as a result, urethane-modified polyester (ua-1) is produced. Here,it is preferable to use the polyvalent isocyanate in an amount of 1 moleequivalent or less, and more preferably 0.5 mole equivalent or less, interms of the isocyanate group, with respect to 1 mole equivalent of thehydroxyl group of polyester resin (a-0). When the amount is greater than1 mole equivalent, a safety problem may occur in which the increase inviscosity within the system becomes prominent, resulting in the loweringof the fixing property, and thus there is a possibility that thepolyvalent isocyanate remains unreacted in the producedurethane-modified polyester resin.

The reaction between the polyester resin and the polyvalent isocyanatemay use any known reaction devices without any limitation. Specifically,examples may include a reactor with stirrer, a twin-screw kneader or thelike. Among these, it is preferable to use a kneading device such as thetwin-screw kneader in view of the reaction efficiency or the homogeneityof the resin. The temperature in the kneader during the reaction ispreferably 100 C or higher from the perspective of sufficientlycompleting the reaction.

The binder resin for toner thus obtained is a polyester resin whichcomprises the urethane-modified polyester resin (ua-1) subjected tourethane extension and polyester resin (a-2) as the main components.Such binder resin may be produced by, for example, a method of reactingpolyester resin (a-0) and polyester resin (a-2) with a polyvalentisocyanate, in addition to the method in which the reaction between saidpolyester resin (a-0) and a polyvalent isocyanate is carried out inadvance to obtain urethane-modified polyester resin (ua-1), and thenpolyester resin (a-2) is added by means of dry blending.

The binder resin for toner preferably has the THF-insoluble portion andthe THF-soluble portion. The THF-insoluble portion is 1 to 40% by mass,and preferably 1 to 25% by mass, while the THF-soluble portion is 99 to60% by mass, and preferably 99 to 75% by mass.

The THF-soluble portion is contained, preferably among the structuralunits derived from alcohol, in the ratios of 80 to 100 mol % of thestructural unit derived from diol (2AU3), 0 to 20 mol % of thestructural unit derived from triol (3AU3), and 0 to 10 mol % of thestructural unit derived from isocyanate compound (IU3), when the sum ofthe structural units derived from alcohol is taken to be 100 mol %.

Further, said THF-insoluble portion is contained, preferably among thestructural units derived from alcohol, in the ratios of 70 to 99 mol %of the structural unit derived from diol (2AU4), 1 to 30 mol % of thestructural unit derived from triol (3AU4), and 0.1 to 35 mol % of thestructural unit derived from isocyanate compound (IU4), when the sum ofthe structural units derived from said alcohols is taken to be 100 mol%.

Said THF-insoluble component is obtained by the method described laterin the Examples, and the content of the THF-soluble component containedtherein is substantially 1% by mass or less. Also, the proportion of theTHF-insoluble component contained in the THF-soluble component issubstantially 1% by mass or less.

The melting temperature of the binder resin for toner is greater than orequal to 110 C. Preferably, it is 110 C or higher and 180 C or lower,and more preferably 120 C or higher and 160 C or lower. By having themelting temperature within these ranges, the resin may satisfy the twoperformances of the fixing property and the offset resistance.

Next, the fifth and sixth aspects according to the present inventionwill be described in detail.

The fifth aspect of the invention is a binder resin for toner,characterized in that it is a urethane-modified polyester resin which isobtained

from 10 to 60% by mass of polyester resin (A) having an OH number of 30to 90 KOH mg/g and glass transition temperature of 0 to 50 C, and

40 to 90% by mass of polyester resin (B) having an OH number less thanor equal to 10 KOH mg/g and a molecular weight of 1000 to 4000, andhaving at least 10 mol % of the structural unit derived from isophthalicacid with respect to 100 mol % that corresponds to the sum of allstructural units derived from the alcohols constituting the polyester,and

from a polyvalent isocyanate;

it contains the structural unit of the following formula [1] in anamount of 1 mol % or less with respect to all alcohol-derived structuralunits:

the melting temperature is greater than or equal to 110 C.

The polyester resin (A) is preferably a polyester resin having arepeating structural unit represented by [[A]COO[B]O(CO)], wherein

[Structure A] has an aliphatic, alicyclic or aromatic structure,

[Structure B] is a structure of formula [II]:

wherein, Ar is a group having an aromatic structure,0≦ m1≦1, 0≦m2≦1,2≦n≦20, andR¹ to R^(2n+2) are groups consisting of elements selected from carbon,hydrogen, oxygen, nitrogen, phosphorous and silicon, and/or covalentbonds, and they may join together to form a cyclic structure or a(double) bond.

More specifically, the polyester resin (A) is generally obtained from acarboxylic acid or its anhydride and carboxylic ester corresponding tostructure A, and from an alcohol corresponding to structure B. Thecarboxylic acid and its anhydride, carboxylic ester and alcohol may bespecifically exemplified by those carboxylic acids, anhydrous carboxylicacids, carboxylic esters and alcohols described for the first aspect ofthe invention. Further, a preferred process for preparation of thepolyester resin (A) may be exemplified by the process for preparation ofpolyester described for the first aspect of the invention.

The polyester resin (A) is preferably a structure in which at least 60mol % of all the structures derived from carboxylic acids of polyesterresin (A) comprise a structure derived from terephthalic acid, and atleast 40 mol % of all the structures derived from alcohols comprise astructure derived from ethylene glycol, on consideration of thepreparation process for the polyester resin which uses theabove-described PET resin as the raw material, or the cost of rawmaterials and supply stability associated therewith, as well as thetoner performance. Further, on consideration of smear resistance in thecase of using the toner to be described later, it is preferable that atleast 20 mol % of all the structures derived from alcohols is astructure derived from neopentyl glycol.

Polyester resin (A) is the component that is believed to attain highmolecular weight mainly by reacting with a polyvalent isocyanate thatwill be described later. Owing to this, when the number of moles of allthe structures derived from alcohols of polyester resin (A) is taken as100 mol %, it is preferred that the proportion of the structure derivedfrom a polyvalent alcohol with a molecular valence of 3 or higher, suchas trimethylolpropane, as previously described, is 2 to 20 mol %, andpreferably 2 to 12 mol %. When the amount of polyvalent alcohol with amolecular valence of 3 or higher is less than 2 mol %, it is difficultto attain high molecular weight in the urethanization reaction that willbe described later, and the offset resistance may become insufficient.On the other hand, when the amount is more than 20 mol %, gelled portionincreases, and the fixing property becomes poor. Meanwhile, the OHnumber of polyester resin (A) is 30 to 90 KOH mg/g. In the presentinvention, when the OH number is less than 30 KOH mg/g, the amountreacting with the polyvalent isocyanate becomes small, that is, theurethane component decreases in amount, and the development durabilityof the toner may become poor. When it exceeds 90 KOH mg/g, the molecularweight of polyester resin (A) tends to lower, making it difficult toattain high molecular weight, and the offset resistance may become poor.

The glass transition temperature of polyester resin (A) is 0 to 50 C.When the glass transition temperature is lower than 0 C, theanti-blocking property may become poor; when it is higher than 50° C.,the fixing property may become poor.

In addition, a preferred molecular weight of polyester resin (A) as thenumber-average molecular weight (B) is 1000 to 4000. If thenumber-average molecular weight is less than 1000, Tg is excessivelylowered and it is susceptible to cause blocking, and if it exceeds 4000,the fixing property may become poor.

The polyester resin (B) previously described is, preferably similar topolyester resin (A), a polyester resin having a repeating structuralunit represented by [[A]COO[B]O(CO)], wherein,

[Structure A] has an aliphatic, alicyclic or aromatic structure,

[Structure B] is a structure of formula [II]:

wherein, Ar is a group having an aromatic structure,0≦m1≦1, 0≦m2≦1,2≦n≦20, andR¹ to R^(2n+2) are groups consisting of elements selected from carbon,hydrogen, oxygen, nitrogen, phosphorous and silicon, and/or covalentbonds, and they may join together to form a cyclic structure or a(double) bond. The preferred carboxylic acids used for preparationthereof, anhydrous carboxylic acids, carboxylic esters and alcohols arethe same as those exemplified for the first aspect of the invention.However, it is characterized in that it comprises, as the structurederived from carboxylic acid, the structure derived from isophthalicacid in an amount of at least 10 mol % of all the structural unitsderived from alcohol in polyester resin (B).

For said polyester resin (B), upon considering the preparation method ofthe polyester resin which uses the above-described PET resin as the rawmaterial, and the cost of raw materials and supply stability associatedtherewith as well as the toner performance, it is preferred that atleast 60 mol %, and preferably 60 to 90 mol % of all the structuresderived from carboxylic acid in polyester resin (B) comprise a structurederived from terephthalic acid, and it is preferred that at least 40 mol% of all the structures derived from alcohol comprise a structurederived from ethylene glycol. Further, on considering the smearresistance when used in a toner as described below, at least 20 mol % ofall the structures derived from alcohol preferably comprise a structurederived from neopentyl glycol.

Polyester resin (B) is a component that is mainly believed to contributeto the low temperature fixing property when used in a toner, since itdoes not react with a polyvalent isocyanate that will be describedlater. Polyester resin (B) is characterized in that it comprises 10 mol% or more of a structure derived from isophthalic acid, when the numberof moles of all the structures derived from alcohol is taken as 100 mol%. It is preferably 10 mol % or greater and 40 mol % or less. By havinga structure as described above, crystallization of polyester resin (B)can be avoided, and consequently it is possible to obtain a binder resinfor toner with good fixing property, as described below. Moreover, byhaving such a structure, it is possible to exhibit good pulverizabilityupon being made into a toner. The OH number of polyester resin (B) is 10KOH mg/g or less, and preferably 7 KOH mg/g or less. When the OH numberexceeds 10 KOH mg/g, the fixing property may be reduced, owing to highpolymerization of the resin resulting from the reaction with polyvalentisocyanate.

The molecular weight of polyester resin (B) is 1000 to 4000 as thenumber-average molecular weight. If the number-average molecular weightis less than 1000, Tg is excessively lowered and it is susceptible tocause blocking, and if it exceeds 4000, the fixing property may becomepoor.

Further, the preferred glass transition temperature of polyester resin(B) is 40 to 80 C. If the glass transition temperature is lower than 40C, the anti-blocking property may become poor; and if it is higher than80° C., the fixing property may become poor.

Also, the content ratio by mass of polyester resin (A) to polyesterresin (B) of the present invention, (A):(B), is 10:90-60:40, and10:90-40:60 is particularly preferred. At a content of polyester resin(A) of less than 10% by mass, the offset resistance may become poor; andat a content of polyester resin (A) of greater than 60% by mass, thefixing property may be poor.

In the fifth aspect of the invention, there is no particular limitationfor the catalyst used in the preparation of polyester resin (A) andpolyester resin (B), but from the perspectives of environmentalprotection as previously mentioned or of the methods for preparation ofpolyester resins using PET as previously mentioned, it is preferable touse a catalyst containing an element selected from titanium, germaniumor aluminum; more preferable is a catalyst containing titanium and/orgermanium; and particularly preferable is a catalyst containingtitanium. Its amount to be used is preferably 0.01 to 1.00% by mass withrespect to the raw materials such as polyester resin, carboxylic acid,alcohol, or the like. The content of the element in the binder resin fortoner as described later is preferably 10 ppm to 1500 ppm, and morepreferably 30 to 1000 ppm.

The content of tin in the polyester resin is preferably 0 to 5 ppm, andmore preferably 0 ppm. As described above, said tin originates from thatcontained in the raw material, when recycled products of polyester areused as the raw material.

The binder resin for toner in the fifth aspect of the invention isobtained from said polyester resin (A), polyester resin (B) andpolyvalent isocyanate. For the polyvalent isocyanate, specific mentionmay be made of the same ones exemplified for the first aspect of theinvention. Also, for the methods for preparation of the binder resin fortoner from polyester resin (A), polyester resin (B) and polyvalentisocyanate, the same method as that mentioned for the first aspect ofthe invention may be taken as an example.

In the binder resin for toner in the fifth aspect of the invention, thestructural unit derived from a compound having the bisphenol A skeletoncomprises 1 mol % or less, preferably 0 mol %, of all structural unitsderived from alcohol. If said structural unit exceeds 1 mol %, the smearresistance which will be described later may be insufficient.

The melting temperature of the binder resin for toner in the fifthaspect of the invention is 110° C. or higher, and preferably 110 C orhigher and 180° C. or lower. The resin having the melting temperaturewithin said range may satisfy both the fixing property and the offsetresistance.

The binder resin for toner for the fifth aspect of the inventioncontains 1 to 40%, preferably 1 to 25%, by mass of the THF-insolublecomponents.

The THF-soluble portion is contained in the resin, preferably in theratios of:

greater than or equal to 5 mol %, preferably 5 to 40 mol %, of thestructural units derived from isophthalic acid (IAU5);

80 to 100 mol % of the structural units derived from diol (2AU5) and 0to 20 mol % of the structural units derived from triol (3AU5) among thestructural units derived from alcohol; and

0 to 10 mol % of the structural units derived from an isocyanatecompound (IU5),

with respect to the sum of the structural units derived from alcoholbeing taken as 100 mol %.

Further, the THF-insoluble portion is contained in the resin, preferablyin the ratios of:

70 to 99 mol % of the structural units derived from diol (2AU6) and 1 to30 mol % of the structural units derived from triol (3AU6) among thestructural units derived from alcohol; and

0.1 to 35 mol % of the structural units derived from an isocyanatecompound (IU6),

with respect to the sum of the structural units derived from alcohol as100 mol %.

The THF-insoluble components are obtained by the method described in theExamples that will be described later, and the THF-soluble componentscontained therein constitutes substantially 1% by mass or less. Also,the proportion of the THF-insoluble components contained in theTHF-soluble components is substantially 1% by mass or less.

The respective compositions of the THF-insoluble components and of theTHF-soluble components in the binder resin for toner in the fifth aspectof the invention are within the same scopes as those for the binderresin for toner in the first aspect.

The binder resins for toner in the first to sixth aspects of theinvention may preferably comprise polyolefin waxes such as polyethylenewax and polypropylene wax, for the purpose of enhancing the performanceof preventing offset on the roller, and the amount of addition ispreferably in the range of 0 to 10% by mass of the binder resin fortoner.

The specific product names corresponding to said polyolefin waxes may bementioned to include, but not limited to, HI-WAX 800P, 400P, 200P, loop,720P, 420P, 320P, 405 MP, 320 MP, 4051E, 2203A, 1140H, NL800, NP055,NP105, NP505, NP805, etc. available from Mitsui Chemicals Inc.

Moreover, the binder resin for toner of the present invention maycontain natural waxes such as ceramic wax, rice wax, sugar wax, lacquerwax, beeswax, carnauba wax, candelilla wax, Montan wax or the like, andthe amount of addition thereof is preferably 0 to 10% by mass of thebinder resin for toner.

Within the scope not impairing the effect of the present invention, itis also possible to add other resins than said polyester resins, such asstyrene copolymers, polyol resins, polyurethane resins, polyamideresins, silicone resins or the like, in the binder resin for toner ofthe present invention.

Hereinafter, a detailed description will be given for the toner, theseventh aspect of the invention.

The toner of the present invention contains at least the binder resinfor toner of the present invention as described above, chargecontrolling agents (CCA), colorants and surface treating agents.

The amount of the binder resin for toner of the present invention ispreferably 50 to 95% by mass of the toner.

Hereinafter, components other than the binder resin for toner will bedescribed in detail.

First, for the colorants, dyes and pigments conventionally known in theart may be used, and specific examples may include carbon black,magnetite, phthalocyanine blue, peacock blue, permanent red, lake red,rhodamine lake, Hanza yellow, permanent yellow, benzidine yellow,nigrosin dye (C.I. NO. 50415), aniline blue (C.I. No. 50405), charcoalblue (C.I. No. azoec Blue 3), chrome yellow. (C.I. NO. 14090),ultramarine blue (C.I. No. 77103), Du Pont oil red (C.I. No. 26105),Orient oil red #330 (C.I. No. 60505), quinoline yellow (C.I. NO. 47005),methylene blue chloride (C.I. NO. 52015), phthalocyanine blue (C.I. NO.74160), Malakite green oxalate (C.I. No. 42000) or the like. The amountof addition is preferably 3-15 part by mass with respect to 100 parts bymass of the binder resin for toner.

For the charge controlling agent, any known charge controlling agent,including nigrosin, quaternary ammonium salts or metal-containing azodyes, may be appropriately selected and used, and the amount used is 0.1to 10 parts by mass with respect to 100 parts by mass of the binderresin for toner, as typically used in the art.

Next, for the surface treating agent, examples include fine powders ofcolloidal silica, alumina, titanium oxide, polytetrafluoroethylene,polyvinylidene chloride, polymethyl methacrylate, polystyrenemicroparticles, silicone or the like, and the amount of addition ispreferably 0.1 to 20 parts by mass with respect to 100 parts by mass ofthe binder resin for toner.

The toner of the present invention may contain polyolefin wax, and theamount thereof is 0 to 10 parts by mass with respect to 100 parts bymass of the binder resin for toner. As polyolefin wax, specific examplesinclude those described for the binder resin for toner in the first tosixth aspects of the invention.

In the process for preparation of the toner of the present inventionusing these materials, the binder resin for toner of the presentinvention, colorants and other additives, as appropriate, aresufficiently mixed in a powder mixer, and then the components arethoroughly mixed by melting and kneading using a heating roll, akneader, or a kneading device called extruder. After cooling thismixture, pulverization and sieving is carried out, particles typicallyhaving a size of 8 to 20 μm are collected, and a surface treating agentis applied onto the particles by powder mixing method to yield a toner.

The toner obtained by the present invention may be used in a variety ofdevelopment processes, for example, cascade development technique,magnetic brush technique, powder cloud technique, touchdown technique,so-called microtoning technique employing as a carrier a magnetic tonerprepared by pulverization, so-called bipolar magnetic toner technique inwhich a desired toner charge is obtained by frictional charging betweenmagnetic toners, or the like, and are not intended to be limited bythese.

Further, the toner obtained by the present invention may be used withvarious fixing techniques. Specifically, examples include oil-less heatrolling, oil-applied heat rolling, flashing, ovening, pressure fixing,or the like. Especially oil-less heat rolling and flashing arepreferred.

Moreover, the toner of the present invention may be used with variouscleaning techniques such as the fur brush technique, blade technique orthe like.

The toner of the present invention is excellent in the fixing propertyand the offset resistance, and surprisingly is also excellent in smearresistance. Smearing property indicates the fixed image, that is, thedegree of transfer of the fixed toner to other paper. More specifically,it indicates the phenomenon in which the fixed toner is subjected tofriction with other paper, thus the surface of this toner soiling thepaper. A toner with excellent smear resistance results in very littletransfer of image, that is, less soiling of other paper, when a sheet ofpaper with fixed image is contacted with other sheet of paper. Becauseof this, even when many sheets of printed documents are prepared bydouble-sided printing or double-sided copying, the toner practicallydoes not soil the image on other sheet of paper and is very preferablein practice.

EXAMPLES

Hereinbelow, the present invention will be explained by the Examples inmore detail, but the present invention is not intended to be limited tothese Examples. Meanwhile, the term “parts” as used herein indicatespercentage by mass (% by mass), unless indicated otherwise.

The melting temperature of the binder resin for toner according to thepresent invention was determined as follows. Measurement is performedunder the following conditions using Shimadzu Flow Tester CFT500D(product of Shimadzu Corporation).

pore on the die: 1 mm in diameter, 1 mm in length

size of sample: 1 cm³

rate of temperature rise: 6 C/min

load: 20 kg/cm²

Then, from the temperature-piston stroke (sample outflow) curve, ½ ofthe difference between the piston stroke values for the temperature atthe start of outflow and for the temperature at the end of outflow isdetermined, and the temperature at the piston stroke value isdetermined. This temperature was taken as the melting temperature.

The glass transition temperature (Tg) in the present invention wasmeasured by differential scanning calorimetry (DSC) using DSC-20 (SeikoElectronic Industry Co. Ltd.). About 10 mg of the sample was subjectedto temperature elevation from −20 C to 100 C at a rate of 10 C/min, andTg was determined at the intersection of the baseline of the curveobtained and the gradient of the endothermic peak. Prior to thismeasurement of temperature elevation, it is preferable to unify thethermal history of the resin by carrying out the operation of firstelevating the temperature of the resin to about 200 C, and aftermaintaining the resin at the temperature for 5 minutes, immediatelycooling the resin to room temperature (25 C).

In the present invention, the amounts of the THF-insoluble component andof the THF-soluble component are determined as follows. Using about 2.5g of the resin and about 47.5 g of THF, a solution with a concentrationof about 5% by mass is prepared (hereinafter, the concentration of saidsolution is referred to as “RC”. RC is a value determined from theprecisely weighed values of the mass of the resin and of the mass ofTHF). That is to say, the mixture is stirred at 25±3 C for 12 hours todissolve the soluble component completely. Then, the solution thusobtained was settled for 16 hours. After the insoluble portion isseparated from the supernatant, the supernatant is analyzed forconcentration (hereinafter, the concentration of the supernatant isreferred to as “SC”. This value is calculated from the precisely weighedvalue of measuring about 5 g of the supernatant, and from measured valueof the mass of the resin remained after the removal of tetrahydrofuranby drying at 150° C. for 1 hour).

The values for the THF-insoluble component and the THF-soluble componentcan be determined from the RC value and the SC value by the followingequation.Ratio of the THF-soluble component=(SC/RC)×100 (%)Ratio of the THF-insoluble component=[(RC−SC)/RC]×100 (%)

Then, the supernatant was removed by decantation from this solution, andthe residue was washed several times with THF. This residue was driedunder reduced pressure at 40 C to yield the THF-insoluble component.

The acid number as used herein indicates the number of mg of potassiumhydroxide required to neutralize 1 g of the resin. The measurement ofthe acid number was determined by neutralization titration. Five gramsof the sample was dissolved in 50 cc of a mixed solvent ofxylene/dimethylformamide (1/1 ratio by mass), a few drops of thephenolphthalein/ethanol solution was added as an indicator, and thentitration was performed with an aqueous solution of 1/10 N KOH. Themoment when the color of the sample solution turned from colorless topurple was taken as the completion point, and the acid number (mg KOH/g)was estimated from the titration amount and the mass of the sample.

Further, the measurement of the OH number in the present invention wasperformed by reverse titration involving the following acid anhydride.To 2 g of the resin, 5 cc of the phthalized reagent (produced in theproportions of pyridine 500 cc/phthalic acid 70 g/imidazole 10 g)prepared separately was added and dissolved, and then the solution wassettled at 100 C for 1 hour. Then, to this resin solution, 1 cc ofwater, 70 cc of tetrahydrofuran, and a few drops ofphenolphthalein/ethanol solution were added, and titration with anaqueous solution of 0.4 N NaOH was carried out. The moment when thecolor of the sample solution turned from colorless to purple was takenas the completion point, and the OH number (KOH mg/g) was estimated fromthe titration amount and the mass of the sample. In addition, thequantitative analysis for metals in the resin according to the presentinvention was carried out by the high-frequency plasma luminescenceanalysis device SPS1200A (available from Seiko Electronic Industry Co.,Ltd.).

The measurements of the molecular weight of the resin and of themolecular weight distribution in the present invention were carried outby means of GPC. The measurement was carried out under the followingconditions, using commercially available monodisperse standardpolystyrene.

Detector: SHODEX RI-71S

Solvent: tetrahydrofuran

Column: KF-G+KF-807L×3+KF800D (connected in series)

Flow rate: 1.0 ml/min,

Sample: 0.25% THF solution

Meanwhile, the reliability of the measurements can be confirmed as theratio Mw/Mn of the NBS706 polystyrene sample (Mw=288,000, Mn=137,000,Mw/Mn=2.11) is obtained as 2.11±0.10 under the above measurementconditions.

Preparative Example 1 for Polyester Resin

In a 5-L four-necked flask equipped with a reflux cooler, a waterseparator, a nitrogen gas inlet, thermometer and a stirrer, 67 mol % ofrecycled PET (weight-average molecular weight: 75000) in the form offlakes, in terms of the ethylene glycol unit in PET, 21 mol % ofneopentyl glycol, 12 mol % of trimethylolpropane, 32 mol % ofterephthalic acid, 9 mol % of benzoic acid, and 0.2% by mass oftetra(2-ethylhexyl)titanate (product of Matsumoto PharmaceuticalIndustry Co., Ltd.; Orgatics TA-30) were placed, and thedepolymerization and dehydrative polycondensation reactions were carriedout at 250 C while introducing nitrogen into the flask. At the pointwhere the acid number of the reaction product reached a predeterminedvalue, the reaction product was withdrawn from the flask, cooled andpulverized to yield Resin 1. Tg and melting temperature of thus obtainedresin were 58.4 C and 131 C, respectively.

Preparative Example 2 for Polyester Resin

In a 5-L four-necked flask equipped with a reflux cooler, a waterseparator, a nitrogen gas inlet, thermometer and a stirrer, 64 mol % ofrecycled PET (weight-average molecular weight: 75000) in the form offlakes, in terms of the ethylene glycol unit in PET, 22 mol % ofneopentyl glycol, 14 mol % of trimethylolpropane, 38 mol % ofterephthalic acid, 7 mol % of benzoic acid, and 0.3% by mass oftetra-n-butyl titanate (product of Matsumoto Pharmaceutical IndustryCo., Ltd.; Orgatics TA-25) were placed, and the depolymerization anddehydrative polycondensation reactions were carried out at 250° C. whileintroducing nitrogen into the flask. At the point where the acid numberof the reaction product reached a predetermined value, the reactionproduct was withdrawn from the flask, cooled and pulverized to yieldResin 2. Tg and melting temperature of thus obtained resin were 60.4 Cand 141 C, respectively.

Preparative Example 3 for Polyester Resin

In a 5-L four-necked flask equipped with a reflux cooler, a waterseparator, a nitrogen gas inlet, thermometer and a stirrer, 60 mol % ofrecycled PET (weight-average molecular weight: 75000) in the form offlakes, in terms of the ethylene glycol unit in PET, 30 mol % ofneopentyl glycol, 10 mol % of trimethylolpropane, 35 mol % ofterephthalic acid, 10 mol % of benzoic acid, and 0.5% by mass oftetraisopropyl titanate (product of Matsumoto Pharmaceutical IndustryCo., Ltd.; Orgatics TA-10) were placed, and the depolymerization anddehydrative polycondensation reactions were carried out at 250 C whileintroducing nitrogen into the flask. At the point where the acid numberof the reaction product reached a predetermined value, the reactionproduct was withdrawn from the flask, cooled and pulverized to yieldResin 3. Tg and melting temperature of thus obtained resin were 61.2° C.and 124 C, respectively.

Preparative Example 4 for Polyester Resin

In a 5-L four-necked flask equipped with a reflux cooler, a waterseparator, a nitrogen gas inlet, thermometer and a stirrer, 63 mol % ofrecycled PET (weight-average molecular weight: 75000) in the form offlakes, in terms of the ethylene glycol unit in PET, 27 mol % of theproduct under the name Actocol KB300 (product of Mitsui-Takeda ChemicalIndustries, Ltd.: propylene oxide adduct of bisphenol A), 10 mol % oftrimethylolpropane, 31 mol % of terephthalic acid, 12 mol % of benzoicacid, and 0.5% by mass of dibutyltin oxide were placed, and thedepolymerization and dehydrative polycondensation reactions were carriedout at 250° C. while introducing nitrogen into the flask. At the pointwhere the acid number of the reaction product reached a predeterminedvalue, the reaction product was withdrawn from the flask, cooled andpulverized to yield Resin 4. Tg and melting temperature of thus obtainedresin were 60.4 C and 124 C, respectively.

The results of preparation of the above-mentioned resins are summarizedin Table 1. TABLE 1 Preparative Examples for polyester resins Resin 1 23 4 PET (mol %) 67 64 60 63 Neopentyl 21 22 30 — glycol (mol %) KB 300(mol %) — — — 27 Trimethylol 12 14 10 10 propane (mol %) Terephthalic 3238 35 31 acid (mol %) Benzoic acid 9 7 10 12 (mol %) Catalyst Tetra(2-Tetra-n- Tetraisopropyl Dibutyltin ethylhexyl) butyl titanate oxidetitanate titanate Amount of catalyst 0.2 0.3 0.5 0.5 (% by mass) Tg(°C.) 58.4 60.4 61.2 60.4 Melting 131 141 124 125 temperature (° C.) THF-(% by 96 93 98 97 soluble mass) portion 2AU1 90 89 91 90 (mol %) 3AU1 1011 9 10 (mol %) THF- (% by 4 7 2 3 insoluble mass) portion 2AU2 87 84 8788 (mol %) 3AU2 13 16 13 12 (mol %)

Hereinbelow, Example 1 will be described in detail as a representativeexample for the mode of carrying out the invention. The same procedureas in Example 1 was taken for Resins 2-4, that is, Examples 2, 3 andComparative Example 1, and the resins and toners obtained therefrom wereevaluated. The results of evaluation are summarized in Table 2.

Example 1

To 100 parts by mass of Resin 1, 6 parts by mass of carbon black(MA-100; product of Mitsubishi Chemical Corp.), 1.5 parts of chargecontrolling agent (BONTRON E-84; product of Orient Chemical Co., Ltd.),and 2.0 parts of polypropylene wax (HI-WAX NP105; product of MitsuiChemicals) were dispersed and mixed in a Henschel mixer, and then themixture was melted and kneaded at 120 C in a double-screw kneader,PCM-30 (product of Ikegai Machinery Co.) to provide a toner compositionin the form of lump. This toner composition was crude pulverized in ahammer mill, and was in turn finely pulverized in a jet pulverizer(product of Nippon Pneumatics Co., IDS2 type), and then classified usinga pneumatic classifier to obtain a fine powder of toner having anaverage particle size of 10 μm (5 μm or lower: 3% by mass, 20 μm orhigher: 2% by mass). Next, to 100 parts by mass of said toner,hydrophobic silica (R-972, product of Aerosil Co.) was added from anexternal source in a ratio of 0.5 parts by mass, and this mixture wasmixed in a Henschel mixer to obtain a toner. Using the particles of thistoner, the fixing property, offset resistance and smear resistance wereinvestigated according to methods (1), (2) and (3) described below.

(1) Fixing Property

After preparing an unfixed image with a copier machine remodeled from acommercially available electrophotographic copier machine, this unfixedimage was fixed using the heat roller fixing device built by remodelingthe fixing part of a commercially available copier machine. The fixingrate of the heat roller was set to 200 mm/sec, and the temperature ofthe heat roller was changed by 5 C to carry out the fixing of toner.Thus obtained fixed image was subjected to friction with a sand eraser(Tombow Pencils Co.) for 10 times under a load of 0.5 kg of weight, andthe image density of before and after the friction test was measured bya Macbeth-type reflective densitometer. The lowest fixing temperature,at each of which the rate of change of the image density was greaterthan or equal to 70%, was taken as the lowest fixing temperature.Further, the heat roller fixing device used herein did not have thesilicone oil supplying device. The environmental conditions were set toambient temperature and ambient pressure (temperature: 22 C, relativehumidity: 55%).

1: lowest fixing temperature≦180 C

2: 200 C≧lowest fixing temperature>180 C

3: lowest fixing temperature>200 C

Among these, “1” was of the level usable as commercial product.

(2) Smear Resistance

According to the evaluation of the fixing property, an unfixed image wasprepared, and this unfixed image was fixed by means of a heat rollerfixing device. Fixing of the toner was carried out at a fixing rate ofheat roller of 250 mm/sec and at a heat roller temperature of 170° C.The solid black powder of the obtained fixed image (I.D.=1.35 to 1.45;measured by a Macbeth-type densitometer) was subjected to friction witha sheet of commercially available copier paper, by going to/from forthree times under a load of 500 g weight. The degree of contamination ofthe copier paper after the friction test was identified by measuring theimage density (I.D.) of the copier paper with a Macbeth-type reflectivedensitometer. The environmental conditions were set to ambienttemperature and ambient pressure (temperature: 22° C., relativehumidity: 55%).

1: I.D.≦0.9 (less contamination)

2: 1.2≧I.D.>0.9

3: I.D.>0.12 (severe contamination)

Among these, “1” and “2” are of the level usable as commercial product.

(3) Offset Resistance

The evaluation of the offset resistance was carried out in accordancewith the measurement of the above-mentioned lowest fixing temperature;specifically, the operation in which, after an unfixed image wasprepared with the copier machined as described above, the fixing processwas carried out by the above-described heat roller fixing device bytransferring the toner image, a sheet of white copier paper was sent tothe corresponding heat roller fixing device under the same conditions,and then it was visually observed whether there occurs any contaminationby toner on the copier paper, was repeated in the state where the settemperature of the heat roller of the heat roller fixing device wassuccessively elevated. The lowest set temperature at which tonercontamination occurred was taken as the offset occurring temperature.The environmental conditions were set to ambient temperature and ambientpressure (temperature: 22 C, relative humidity: 55%).

1: offset occurring temperature≧210 C

2: 210 C>offset occurring temperature≧170 C

3: 170 C>offset occurring temperature

Among these, “1” is of the level usable as commercial product.

As is obvious from the results of Table 2, toners 1-3 using the binderresins for toner prepared according to the present invention wereexcellent not only in the fixing property and offset resistance but alsosmear resistance. TABLE 2 Evaluation Results for toner Example/Comp.Example No. Comp. Example 1 Example 2 Example 3 Example 1 Resin Resin 1Resin 2 Resin 3 Resin 4 Fixing property 1 1 1 1 smear resistance 2 2 2 3Offset 1 1 1 1 resistance

Next, preparation and evaluation of the binder resins for toner of theurethane-modified polyester type and the toners were carried out. Forthe evaluation of toner, the fixing property, offset resistance, smearresistance and development durability were tested. The evaluation of thefixing property and offset resistance was carried out according to theprocedures (4) and (5) below, by changing the evaluation conditions.Also, the evaluation of development durability was carried according tothe procedure (6) below. Specific terms for these evaluation proceduresare described below.

(4) Fixing Property

After preparing an unfixed image with a copier machine remodeled from acommercially available electrophotographic copier machine, this unfixedimage was fixed using the heat roller fixing device built by remodelingthe fixing part of a commercially available copier machine. The fixingrate of the heat roller was set to 300 mm/sec, and the temperature ofthe heat roller was changed by 5 C to carry out the fixing of toner.Thus obtained fixed image was subjected to friction with a sand eraser(Tombow Pencils Co.) for 10 times under a load of 0.5 kg of weight, andthe image density of before and after the friction test was measured bya Macbeth-type reflective densitometer. The lowest fixing temperature,at each of which the rate of change of the image density was greaterthan or equal to 70%, was taken as the lowest fixing temperature.Further, the heat roller fixing device used herein did not have thesilicone oil supplying device. The environmental conditions were set toambient temperature and ambient pressure (temperature: 22 C, relativehumidity: 55%).

1: lowest fixing temperature≦160 C

2: 170 C≧lowest fixing temperature>160 C

3: 180 C≧lowest fixing temperature>170 C

4: 190 C≧lowest fixing temperature>180 C

5: lowest fixing temperature>190 C

Among these, “1” to “4” were of the level usable as commercial product.

(5) Offset Resistance

The evaluation of the offset resistance was carried out in accordancewith the measurement of the above-mentioned lowest fixing temperaturedescribed in Section (4); specifically, the operation in which, after anunfixed image was prepared with the copier machined described above, thefixing process was carried out by the above-described heat roller fixingdevice by transferring the toner image, a sheet of white copier paperwas sent to the corresponding heat roller fixing device under the sameconditions, and then it was visually observed whether there occurs anycontamination by toner on the copier paper, was repeated in the statewhere the set temperature of the heat roller of the heat roller fixingdevice was successively elevated. The lowest set temperature at whichtoner contamination occurred was taken as the offset occurringtemperature. The environmental conditions were set to ambienttemperature and ambient pressure (temperature: 22 C, relative humidity:55%).

1: offset occurring temperature≧240 C

2: 240 C>offset occurring temperature≧220 C

3: 220 C>offset occurring temperature≧210 C

4: 210 C>offset occurring temperature

Among these, “1”, “2” and “3” are of the level usable as commercialproduct.

(6) Development Durability

After performing a photographic test continuously for 100,000 sheets ofpaper with a commercially available copier machine (product of Toshiba,Precio 5560), an evaluation was carried out on the number of sheets atwhich deterioration of the image density and image quality begins.

1: no deterioration at 70,000 sheets or more

2: deterioration in the range of 50,000 to less than 70,000 sheets

3: deterioration at less than 50,000 sheets

Among these, “1” and “2” are of the level usable as commercial product.

Preparative Example for Urethane-Modified Polyester Resin (1)

The preparation of polyester resins (a-0) and (a-2) was carried out inthe following manner. A specific illustration on the procedure for Resina0-1 will be presented. Resins a0-2, a0-3 and a2-1 to a2-5 were obtainedby the same procedure as in that for Resin a0-1, except that thecatalyst, amount of catalyst addition and the monomer composition werechanged to the blending ratios indicated in Table 3 and Table 4. Theacid numbers and the OH numbers of the resins thus obtained are alsopresented in Table 3 and Table 4.

In a 5-L four-necked flask equipped with a reflux cooler, a waterseparator, a nitrogen gas inlet, thermometer and a stirrer, with respectto 100 mol % of the number of moles of all alcoholic components, 43 mol% of recycled PET (weight-average molecular weight: 75000) in the formof flakes, in terms of the ethylene glycol unit in PET, 43 mol % ofneopentyl glycol, 9 mol % of triethylene glycol, 5 mol % oftrimethylolpropane, 48 mol % of terephthalic acid, and 0.2% by mass oftetra(2-ethylhexyl) titanate (product of Matsumoto Pharmaceutical Co.,Ltd.; Orgatics TA-30) were placed, and the depolymerization anddehydrative polycondensation reactions were carried out at 250° C. whileintroducing nitrogen into the flask. At the point where the acid numberof the reaction product reached the value indicated in Table 3, thereaction product was withdrawn from the flask, cooled and pulverized toyield Resin a0-1. TABLE 3 Preparative Example for polyester resin (a-0)Resin a0-1 a0-2 a0-3 PET(mol %) 43 58 50 Neopentyl 43 25 — glycol(mol %)Bisphenol A-2- — — 21 propylene oxide adduct(mol %)* Triethylene 9 9 18glycol(mol %) Trimethylol 5 8 8 propane(mol %) Terephthalic 48 33 34acid(mol %) Catalyst Tetra(2- Tetra-n- Dibutyltin ethylhexyl) butyloxide titanate titanate Amount of 0.2 0.1 0.5 catalyst(wt %) Acidnumber(mg 8 11 8 KOH/g) OH number(mg KOH/g) 54 62 59*Product name: Actocol KB-300

TABLE 4 Preparative Example for polyester resin (a-2) Resin a2-1 a2-2a2-3 a2-4 a2-5 PET (mol %) 65 40 73 80 67 Neopentyl 30 47 21 17 — glycol(mol %) Bisphenol A-2- — — — — 29 propylene oxide adduct (mol %)*Trimethylol 5 13 6 3 4 propane (mol %) Terephthalic 33 63 30 21 37 acid(mol %) Benzoic 15 11 14 9 13 acid (mol %) Catalyst Tetra Tetra(2-Tetramethyl Titanium Dibutyltin n- ethylhexyl) titanate ethyl oxidebutyl titanate acetoacetate titanate Amount of catalyst 0.2 0.3 0.5 0.50.5 (wt %) Acid number (mg KOH/g) 17 12 36 25 35 OH number (mg 8 7 9 6 5KOH/g)*Product name: Actocol KB-300

Hereinbelow, Example 4 will be described in detail as a representativeexample for the mode of carrying out the invention. The same procedureas in Example 4 was taken for Resins 6 to 12, that is, Examples 5-8 andComparative Examples 2 to 4, and the resins and toners obtainedtherefrom were evaluated. For these, the blending ratios of Resins (a-0)and (a-2) or the amount of addition of tolylene diisocyanate, theresults for resin evaluation, for quantitative analysis of metalcontents in the resins and for toner characteristics evaluation arepresented in Table 5 along with Example 4.

Example 4

30% by mass of Resin a0-1, 70% by mass of Resin a2-1 and 2.2% by mass oftolylene diisocyanate were fed to a double-screw extruder-kneader(product of Kurimoto, Ltd., KEX-40) at a total resin flow rate of 20kg/h, and a kneading reaction was carried out at a temperature of 180 Cand at a screw rotation of 150 rpm, to yield urethane-modified polyesterresin 5. Thus obtained resin had Tg of 58.4 C and a melting temperatureof 144 C.

To 100% by mass of urethane-modified polyester resin 5, 6% by mass ofcarbon black (MA-100; product of Mitsubishi Chemical Corp.), 1.0% bymass of charge controlling agent (BONTRON E-84; product of OrientChemical Co., Ltd.), and 2.0% by mass of polypropylene wax (HI-WAXNP105; product of Mitsui Chemicals) were dispersed and mixed in aHenschel mixer, and then the mixture was melted and kneaded at 120 C andat 150 rpm in a double-screw kneader, PCM-30 (product of IkegaiMachinery Co.) to provide a toner composition in the form of lump. Thistoner composition was crude pulverized in a hammer mill, and was in turnfinely pulverized in a jet pulverizer (product of Nippon Pneumatics Co.,IDS2 type) and then classified using a pneumatic classifier to obtain afine powder of toner having an average particle size of 10 μm (5 μm orlower: 3% by mass, 20 μm or higher: 2% by mass). Next, to 100% by massof said toner, hydrophobic silica (R-972, product of Aerosil Co.) wasadded from an external source in a ratio of 0.5% by mass, and thismixture was mixed in a Henschel mixer to obtain a toner. Using theparticles of this toner, the fixing property, smear resistance, offsetresistance and development durability were investigated. The results arepresented in Table 5.

As is obvious from the results of Table 5, the toners using the binderresins 5 to 9 for toner prepared according to the present invention wereexcellent not only in the fixing property, offset resistance anddevelopment durability but also smear resistance.

Next, preparation and evaluation of the binder resins for toner usingother urethane-modified polyester resins and the toners were carriedout. For the evaluation, the following test items were added in additionto the smear resistance, fixing property (4), offset resistance (5) anddevelopment durability. TABLE 5 Evaluation results for the properties ofthe binder resins for toner and of toners Example/Comp. Example No.Comp. Example 4 Example 5 Example 6 Example 7 Example 8 Comp. Example 2Comp. Example 3 Example 4 Resin Resin 5 Resin 6 Resin 7 Resin 8 Resin 9Resin Resin Resin 10 11 12 Resin Type a0-1 a0-2 a0-2 a0-1 a0-1 a0-3 a0-2a0-1 a-0 (% by mass) 30 40 35 25 50 45 25 30 Resin Type a2-1 a2-2 a2-3a2-4 a2-2 a2-3 a2-5 a2-5 a-2 (% by mass) 70 60 65 75 50 55 75 70Tolylene diisocyanate(% by mass) 2.2 2.5 1.8 1.5 3.6 3.7 1.9 2.4 Tg(°C.) 58.4 62.8 58.3 56.1 57.2 60.3 58.7 57.6 Melting temperature(° C.)144 149 128 122 131 138 123 135 Metal Sn 0 0 0 0 0 1062 1721 697 contentTi 235 186 928 441 207 753 29 116 (ppm) Fixing property(4) 2 2 2 2 2 2 22 smear resistance 1 1 1 1 1 3 3 3 Offset resistance(5) 1 1 1 1 1 1 1 1Development durability 1 1 1 1 1 1 1 1 THF- (% by mass) 90 86 95 97 9492 97 93 soluble 2AU3(mol %) 95 88 93 96 95 93 96 96 3AU3(mol %) 5 12 74 5 7 4 4 IU3(mol %) 3 3 2 2 5 6 3 4 THF- (% by mass) 10 14 5 3 6 8 3 7insoluble 2AU4(mol %) 95 92 94 92 95 92 92 95 3AU4(mol %) 5 8 6 8 5 8 85 IU4(mol %) 13 12 10 14 13 15 23 17

(7) Toner Pulverizability

The particle size distribution of the fine particles obtained by finelypulverizing by a jet pulverizer, a product of Nippon Pneumatics Co.(Type 1 mill) was measured with a Coulter counter and was graded asfollows by means of the 50% particle size.

1: 50% of the particle size being greater than or equal to 6.5 μm andless than or equal to 8.5 μm

2: 50% of the particle size being greater than or equal to 8.5 μm toless than 10 μm

3: 50% of the particle size being greater than or equal to 10 μm to lessthan 11.5 μm

4: 50% of the particle size being greater than or equal to 11.5 μm

Among these, “1”, “2” and “3” are of the levels usable as commercialproduct.

(8) Anti-Blocking Property

The degree of cohesion of the toner powder after storage for 3 days at atemperature of 50 C was evaluated visually.

1: no blocking

2: partial blocking

3: severe blocking

Among these, “1” and “2” are of the level usable as commercial product.

Preparative Example for Urethane-Modified Polyester Resin (2)

Preparation of polyester resin (A) and (B) was carried out by thefollowing procedure. A specific illustration on Resin A-1 will bepresented. Resins A-2 to A-7 and B-1 to B-7 were obtained by the sameprocedure as in that for Resin A-1, except that the monomer compositionwas changed to the blending ratios indicated in Table 6 and Table 7. Theacid numbers, OH numbers, Tg and Mn of the resins thus obtained are alsopresented in Table 6 and Table 7. TABLE 6 Preparative Example forpolyester resin (A) Feed composition Property of resin(A) NeopentylTriethylene Trimethylol Terephthalic Acid OH Resin PET glycol glycolpropane acid number number Tg No. (mol %) (mol %) (mol %) (mol %) (mol%) (mgKOH/g) (mgKOH/g) (° C.) Mn A-1 60 25 8 7 28 7 68 38 2700 A-2 65 208 7 26 8 61 44 3400 A-3 60 27 10  3 29 5 52 43 3300 A-4 61 26 9 4 25 1178 26 1500 A-5 60 32 8 — 28 10 57 36 2300 A-6 59 35 — 6 32 5 62 54 3200A-7 60 32 5 3 35 9 26 41 4700

TABLE 7 Preparative Example for polyester resin (B) Feed compositionProperty of resin (B) Neopentyl Isophthalic Terephthalic Benzoic Acid OHResin PET(mol glycol acid acid acid number number Tg No. %) (mol %) (mol%) (mol %) (mol %) (mgKOH/g) (mgKOH/g) (° C.) Mn B-1 70 30 32 — 6 25 356 2500 B-2 70 30 23 — 10 4 7 50 3200 B-3 70 30 32 — 12 34 4 44 1300 B-470 30 38 — 10 38 5 61 3100 B-5 70 30 — 32 8 23 4 55 2200 B-6 70 30 30 —— 15 6 68 4500 B-7 70 30 37 — 8 25 12 63 3700

In a 5-L four-necked flask equipped with a reflux cooler, a waterseparator, a nitrogen gas inlet, thermometer and a stirrer, with respectto 100 mol % of the number of moles of all alcoholic components, 60 mol% of recycled PET (weight-average molecular weight: 75000) in the formof flakes, in terms of the ethylene glycol unit in PET, 25 mol % ofneopentyl glycol, 8 mol % of triethylene glycol, 7 mol % oftrimethylolpropane, 28 mol % of terephthalic acid, and 0.3% by mass oftetra(2-ethylhexyl) titanate (product of Matsumoto PharmaceuticalIndustry Co., Ltd.; Orgatics TA-30) were placed, and thedepolymerization and dehydrative polycondensation reactions were carriedout at 250 C while introducing nitrogen into the flask. At the pointwhere the acid number of the reaction product reached the valueindicated in Table 6, the reaction product was withdrawn from the flask,cooled and pulverized to yield Resin A-1.

Hereinbelow, Example 9 will be described in detail as a representativeexample for the mode of carrying out the invention. The same procedureas in Example 1 was taken for Resins 14 to 29, that is, Examples 10 to24 and Comparative Example 5, and the resins and toners obtainedtherefrom were evaluated. For these, the blending ratios of thepolyester resin (A) and the polyester resin (B), or the amount ofaddition of tolylene diisocyanate, the results for resin evaluation (Tgand melting temperature), for quantitative analysis of metal contents inthe resins and for toner characteristics evaluation are presented inTable 8 and Table 9 along with Example 9. TABLE 8 Evaluation results forthe properties of the binder resins for toner and for tonersExample/Comp. Example No. Example Example Example Example ExampleExample Example Example Example 9 10 11 12 13 14 15 16 17 Resin ResinResin Resin Resin Resin Resin Resin Resin Resin 13 14 15 16 17 18 19 2021 Resin A Type A-1 A-1 A-1 A-2 A-3 A-4 A-1 A-2 A-3 (% by mass) 30 15 5040 30 25 30 60 35 Resin B Type B-1 B-1 B-1 B-2 B-3 B-4 B-2 B-4 B-2 (% bymass) 70 85 50 60 70 75 70 40 65 Tolylene diisocyanate (% 2.5 1.8 3.22.8 2.6 4.5 1.7 3.1 1.7 by mass) Tg (° C.) 57.9 56.8 58.6 59.8 51.1 63.356.1 60.4 54.9 Melting temperature (° C.) 138 131 151 139 128 152 125127 119 Metal Sn 0 0 0 0 0 0 0 0 0 content Ti 241 252 239 254 251 248257 254 249 (ppm) Fixing property (4) 1 1 1 1 1 1 1 1 1 smear resistance1 1 1 1 1 1 1 1 1 Offset resistance (5) 1 2 1 1 1 1 1 1 2 Developmentdurability 1 1 1 1 1 1 1 1 1 Pulverizability 1 1 1 1 1 1 1 1 1Anti-blocking property 1 1 1 1 2 1 1 1 1 THF- (% by mass) 91 94 84 88 9586 97 92 96 soluble 2AU5 (mol %) 99 100 97 98 100 100 98 97 99 3AU5 (mol%) 1 1 3 2 4 4 2 3 1 IU5 (mol %) 3 1 4 4 3 3 3 4 3 IAU5 (mol %) 24 30 2116 24 33 17 21 16 THF- (% by mass) 9 8 16 12 5 14 3 8 4 insoluble 2AU6(mol %) 93 93 93 93 97 96 93 93 97 3AU6 (mol %) 7 7 7 7 3 4 7 7 3 IU6(mol %) 16 26 12 12 16 32 16 15 13

TABLE 9 Evaluation results for the properties of the binder resins fortoner and for toners Example/Comp. Example No. Example Example ExampleExample Example Example Example Comp. 18 19 20 21 22 23 24 Example 5Resin Resin 22 Resin 23 Resin 24 Resin 25 Resin 26 Resin 27 Resin 28Resin 29 Resin A Type A-5 A-6 A-7 A-1 A-1 A-1 A-2 A-4 (% by mass) 40 3530 35 35 35 80 5 Resin B Type B-1 B-1 B-1 B-5 B-6 B-7 B-1 B-1 (% bymass) 60 65 70 65 65 65 20 95 Tolylene diisocyanate (% by 2.7 2.5 2.42.4 2.3 2.5 5.1 1.8 mass) Tg(° C.) 59.4 66.4 59.1 58.7 63.1 61.2 58.753.4 Melting temperature (° C.) 134 142 124 134 136 134 129 109 Metal Sn0 0 0 0 0 0 0 0 content Ti 253 248 254 253 249 254 255 242 (ppm) Fixingproperty (4) 1 4 2 4 4 4 4 3 smear resistance 1 1 1 1 1 1 1 2 Offsetresistance (5) 3 3 3 1 1 1 1 4 Development durability 1 1 1 1 1 1 2 3Pulverizability 2 2 1 3 3 3 3 4 Anti-blocking property 1 1 1 1 1 1 2 3THF- (% by mass) 88 86 96 92 93 91 85 97 soluble 2AU5 (mol %) 100 99 10098 98 98 95 100 3AU5 (mol %) 0 1 <1 2 2 2 5 <1 IU5 (mol %) 3 3 3 4 3 3 81 IAU5 (mol %) 21 24 22 0 21 27 8 31 THF- (% by mass) 12 14 4 8 7 9 15 3insoluble 2AU6 (mol %) 100 94 97 93 93 93 93 96 3AU6 (mol %) 0 6 3 7 7 77 4 IU6 (mol %) 15 12 21 12 16 14 12 71

Example 9

30% by mass of Resin A-1, 70% by mass of Resin B-1 and 2.5% by mass oftolylene diisocyanate, were fed to a double-screw extruder-kneader(product of Kurimoto, Ltd., KEX-40) at a total resin flow rate of 20kg/h, and a kneading reaction was carried out at a temperature of 175°C. and at a screw rotation of 150 rpm, to yield a urethane-modifiedpolyester resin 13.

To 100% by mass of this urethane-modified polyester resin 13, 6% by massof carbon black (MA-100; product of Mitsubishi Chemical Corp.), 1.0% bymass of charge controlling agent (BONTRON E-84; product of OrientChemical Co., Ltd.), and 2.0% by mass of polypropylene wax (HI-WAXNP105; product of Mitsui Chemicals) were dispersed and mixed in aHenschel mixer, and then the mixture was melted and kneaded at 120° C.and at 150 rpm in a double-screw kneader, PCM-30 (product of IkegaiMachinery Co.) to provide a toner composition in the form of lump. Thistoner composition was crude pulverized in a hammer mill, and was in turnfinely pulverized in a jet pulverizer (product of Nippon Pneumatics Co.,IDS2 type) and then classified using a pneumatic classifier to obtain afine powder of toner having an average particle size of 8.5 μm. Next, to100% by mass of said toner, hydrophobic silica (R-972, product ofAerosil Co.) was added from an external source in a ratio of 0.5% bymass, and this mixture was mixed in a Henschel mixer to obtain a toner.Using the particles of this toner, the fixing property, offsetresistance and development durability were investigated.

As is obvious from the results in Table 8 and Table 9, the toners usingresins 1 to 9 for toner prepared according to the present invention allhave excellent balance of toner performance.

1. A binder resin for toner comprising a polyester structure comprisinga structure derived from carboxylic acid and a structure derived fromalcohol, wherein the polyester structure contains the structural unit ofthe following formula [I] in an amount of 1 mol % or less with respectto all the structural units derived from alcohol:

the content of tin is 5 ppm or less; the content of an element selectedfrom titanium, germanium and aluminum ranges from 10 ppm to 1500 ppm;the melting temperature is 110° C. or higher, and the resin furthercomprises 0.1 to 10 mol % of a structural unit derived from isocyanatecompound based on the sum of all the structural units derived fromcarboxylic acid and of all the structural units derived from alcoholequaling 100 mol %.
 2. (canceled)
 3. The binder resin for toneraccording to claim 1, wherein binder resin comprises 0 to 40% by mass ofTHF-insoluble components and 100 to 60% by mass of THF-solublecomponents.
 4. The binder resin for toner according to claim 1, whereinat least 60 mol % of the structures derived from carboxylic acidcomprise a structure derived from terephthalic acid, at least 40 mol %of the structural units derived from alcohol comprise a structurederived from ethylene glycol, and at least 75 mol % of the structuralunits derived from alcohol comprise structures derived from ethyleneglycol and neopentyl glycol.
 5. The binder resin for toner comprising apolyester structure comprising a structure derived from carboxylic acidand a structure derived from alcohol, wherein the binder resin isobtained from 10 to 60% by mass of polyester resin (A) having an OHnumber of 30 to 90 KOH mg/g and glass transition temperature of 0 to 50°C., and 40 to 90% by mass of polyester resin (B) having an OH number of10 KOH mg/g or less and a molecular weight of 1000 to 4000, andcomprising at least 10 mol % of a structure derived from isophthalicacid, with respect to 100 mol % of all the units derived from thealcohol constituting the polyester, and from polyvalent isocyanate; thestructural unit of the following formula [I] constitutes 1 mol % or lessof all the structural units derived from alcohol;

the melting temperature is 110° C. or higher.
 6. The binder resin fortoner according to claim 5, wherein polyester (A) has a number-averagemolecular weight of 1000 to 4000 and comprises 2 to 20 mol % ofstructural units derived from polyvalent alcohol with a molecularvalence of 3 or higher, with respect to 100 mol % of all the unitsderived from the alcohol constituting the polyester; and that polyester(B) has a glass transition temperature of 40 to 80° C.
 7. A tonercomprising the binder resin for toner described in claim
 5. 8. A tonercomprising the binder resin for toner described in claim 1.